This renewal application is for funds to continue operation of the mass spectrometry facility at Michigan State University. A double focusing mass spectrometer has been acquired for exact mass measurements, for field ionization and field desorption work, and for analyses of metastable decompositions. Primary goals of the facility will be to provide low and high resolution mass spectral data and special techniques in support of a wide variety of research of importance in the biomedical fields. Core research will include continued development of computer programs for stable isotope abundance measurements and for studies of drug metabolism by the technique involving static changes in the accelerating voltage to focus ions, development of interfaces and programs for computer control of mass spectrometer functions such as magnetic field strength, ion source voltage, electric sector voltage (high resolution), etc. A comprehensive software package will be developed for clinical use, which will provide extensive computer analysis of mass spectral data in the diagnosis of diseases by urine analysis of steroids, acidic metabolites, sugars and amino acids, utilization of mass chromatograms and other approaches to evaluate the potential of gas chromatography-mass spectrometry for determination of biochemical profiles, and assessment of biochemical profiles for early or subclinical recognition of diseases.